At least one incidence of the disease, which causes lambs and calves to be born stillborn or with severe abnormalities, has already been reported in the region this year.

The case comes as figures released by the Animal Health and Veterinary Laboratories Agency (AHVLA), reveal that at least 26 sheep and cattle holdings in Suffolk have been affected by the condition since January 2012.

A further 17 herds and flocks in Essex have also had confirmed cases of the Schmallenberg.

It is possible that the number of cases is greater as the disease is “non-notifiable”, meaning although livestock owners are advised to contact vets with suspected infections, they are not obliged to do so.

The NFU has called for a vaccine to be made available for the virus, which is spread by midges, as soon as possible.

Chris Partridge, who has a flock of 110 breeding ewes in Kersey Tye, was affected by Schmallenberg last year and has already seen one ewe with the virus.

He added: “It is definitely a concern. We’ve lambed two sheep this year and we had a small group at Christmas and we had one case of Schmallenberg in that 15 ewes.”

Mr Partridge, who last year was forced to deliver a clutch of deformed and dead lambs, said he hoped that his main flock would have developed an immunity to the virus.

He added: “There has been a massive problem in other parts of the country - in the midlands and further across - but from my point of view, I am reasonably optimistic that we won’t be getting a problem this year.

“Scientists have told us that those sheep that have been infected in previous years should be immune. But we don’t know if all of the sheep have been affected so it is possible that some of them have lambs with Schmallenberg. We also don’t know if immunity is for life that is one of the main questions we are asking now.”

Gerald Ketley, who has 1,100 breeding ewes on land in Fingringhoe, near Colchester, said: “We are fearful yes. We have built up our flock again and they are in lamb but it is unknown whether we will suffer from Schmallenberg or not.

“We’re hearing lots of stories in northern parts where they are losing a considerable amount of lambs, up to 80%, through this. But at the moment, we haven’t seen massive problems down here.

“We don’t start lambing until the end of March and the start of April so we won’t know until we get nearer the lambing I suppose. We’re on tenterhooks. We have had about 50 lambs and we haven’t seen any problem with them but it is the unknown.”

Mr Ketley, who previously farmed around Colchester Market and Ipswich Road, added: “Because of the deformities and everything it is rather a worry. There is just nothing you can do about it. We just seem to go down with more and more issues and diseases.”

Andrew Foulds, Livestock manager of the Elveden Estate, lost 8% of his lambs to the virus last year. But speaking yesterday he said they had lambed 1,150 ewes without a trace of the virus. He added: “The Almighty has been good to us”.

James Coe of Layer Marney Lamb in Stanway, has 600 breeding ewes that are expected to lamb in March.

He said: “We didn’t have any cases of it last year, but we are obviously fearful of it. It is one of those things, you’re fearful of it because there is nothing you can do about it until we have a vaccine.”

A spokesman for the NFU said the presence of Schmallenberg is a “big concern.” He added: “This is why we want a vaccine to be made available as soon as possible. Hopefully it will be available later this year but that will be too late for this year’s lambing. We know from our experience with blue tongue that our farmers are very quick to make use of a vaccine when it is available.”

He added: “Even if only a small amount of farms are affected, it can have a serious financial impact on individual farms.”

A spokesman for Defra said a vaccine would be available soon but necessary safety checks had not yet been completed.